1. Field of the Invention
The present invention relates to optical elements comprising a macromolecular liquid crystal composition. The element includes a light scattering element, a light modulation element (an element for changing the phase, wavelength, strength, polarized face and so on of light), a dimming element (element for changing the transmission factor, reflection factor, and so on of light), a rewritable recording element, an optical recording element, a optical waveguide designed to control the transmission of light, a light switch designed to switch light, an optical element applicable to a photo coupler or the like designed to conduct photoconnection. The invention also relates to a method of manufacturing optical elements, and macromolecular liquid crystal composition for an optical element.
2. Description of Related Art
Attention has been paid to a macromolecular liquid crystal, as a novel functional material. Known are a rewritable recording element, which is an application of the macromolecular liquid crystal and capable of recording images reversibly by an external stimulus, an optical recording element, further an optical compensating element, an orientation film (JP-A No. 63-223066, JP-A No. 62-14114, JP-A No. 2-42415, JP-A No. 2-3021, JP-A No. 3-59622) and the like. Generally these elements are composed of a macromolecular liquid crystal formed on a substrate. Various examples of these constructions are illustrated, for example, in Polym. Commun. Vol. 24, 364 (1983), Japan Display, 290 (1986).
Also, to improve a function of a macromolecular liquid crystal, JP-A No. 3-284988 proposes a light scattering type recording element capable of rewriting, an element having two electrodes sandwiching a composite film where the macromolecular liquid crystal is dispersed in a granular form in a resin, or macromolecule. In the element, local heating is carried out with laser or the like to reversibly change one portion of it from light scattering condition into transparent condition to effect a recording operation. According to the publication, by dispersing the macromolecular liquid crystal in a granular shape into the macromolecule, refractive index difference at their interface is caused so that contrast and resolution can be improved. Further, a specific method of manufacturing the light scattering type optical recording element is also described. The manufacturing method comprises the steps of mixing a precursor, i.e., a mesogen monomer of the macromolecular liquid crystal is mixed with a macromolecular binder precursor, thermally annealing them at a temperature such that the mesogen monomer shows a liquid crystal phase, to separate the mesogen monomer phase from the macromolecular binder precursor phase, polymerizing each of them with ultraviolet ray or the like, to make a composite film where the macromolecular liquid crystal is dispered in the binder resin, in a granular shape.
However, in the above-described art satisfactory contrast cannot be obtained. There remains improvement on structural stability.